Promising young linebacker Michael Mauti will miss the 2009 season after suffering a serious knee injury Sunday, Penn State announced this afternoon.

A sophomore battling for one of the starting linebacker positions, Mauti tore the ACL in his right knee, Penn State said, and will have surgery within the next three weeks. Rehabilitation will take about nine months.

The injury means that Penn State's likely starting linebackers this fall will include two incumbents, Navorro Bowman at outside linebacker and Josh Hull at middle linebacker. Captain and former starter Sean Lee -- who missed all of 2008 with a torn ACL in his right knee -- is the likely starter at the other outside linebacker spot. Also in the mix is Nathan Stupar, who could start on the outside if Lee moves to the middle to supplant Hull.

Mauti, son of former Penn State and NFL wide receiver Rich Mauti, was one of three true freshmen to play in every Penn State game last year. He was a force on special teams but also played a lot at backup linebacker, including most impressively in the victory over Michigan -- when he had seven tackles.

He will still have three years of eligibility left when he returns, hopefully, for the 2010 season.